Visualization of Ligand-Bound Ectodomain Assembly in the Full-Length Human IGF-1 Receptor by Cryo-EM Single-Particle Analysis.

Tyrosine kinase receptor of insulin-like growth factor 1 receptor (IGF-1R) and insulin receptor (IR) bind to hormones, such as insulin, IGF-1, and IGF-2, and transduces the signals across the cell membrane. However, the complete structure of the receptor and the signal transduction mechanism remains unclear. Here, we report the cryo-EM structure of the ligand-bound ectodomain in the full-length human IGF-1R. We reconstructed the IGF-1R/insulin complex at 4.7 Å and the IGF-1R/IGF-1 complex at 7.7 Å. Our structures reveal that only one insulin or one IGF-1 molecule binds to and activates the full-length human IGF-1R receptor.